Refrigeration Heat Exchangers in Industrial Chiller systems
Condenser
Classification (by cooling method): Air-cooled condensers, water-cooled condensers (including shell-and-tube, double-pipe, shell-and-coil, spiral plate, and submerged types), evaporative condensers, and spray condensers.
Air-Cooled Condenser
Typical Applications: Commonly used in refrigerators, freezers, small air conditioners, refrigerated vehicles, automotive air conditioning, and other small-scale refrigeration units.
Advantages
- No water required
- Simple installation
- Can be placed on rooftops
Disadvantages
- Low heat transfer coefficient
- Significantly affected by ambient temperature
- Can worsen the local environment
- Difficult to clean dust
Limitation: Typically used only in fluorocarbon (freon) refrigeration systems.
Classification: Based on air movement, they can be divided into natural convection air-cooled condensers and forced convection air-cooled condensers.
Features: Higher power consumption, more noise, but higher heat transfer coefficient.
Water-Cooled Condenser
Shell-and-Tube Water-Cooled Condenser
| Features | Applications |
|---|---|
| High heat transfer coefficient | Large and medium-sized ammonia refrigeration systems |
| Compact footprint | |
| Easy to clean; high water consumption, bulky and heavy |
Horizontal Shell-and-Tube Condenser
Typical Applications: Ammonia or fluorocarbon (freon) refrigeration systems.
Double-Pipe (Tube-in-Tube) Condenser
Positive Features
- High heat transfer coefficient
- Compact footprint
- Simple structure
Negative Features
- High metal consumption
- Difficult to clean
- High water-side pressure drop
Shell-and-Coil Condenser
Features: Simple structure; cannot be cleaned mechanically, requires strict water quality, needs regular chemical cleaning.
Spiral Plate Condenser
Advantages
- Small volume
- Lightweight
- High heat transfer coefficient
Limitations
- Not suitable for high pressures
- Internal cleaning and maintenance are difficult
- Requires strict water quality
Evaporative Condenser
Unlike other condensers, the evaporative condenser is neither purely air-cooled nor water-cooled. It combines the advantages of both air and water cooling, achieving high heat dissipation efficiency.
Key Features
- Water-saving
- Low cost
- Simple structure
- Easy scale removal
- Compact size
Spray Condenser
| Advantages | Disadvantages |
|---|---|
|
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Evaporator
Evaporators are classified into dry expansion (direct expansion) evaporators and flooded (recirculating) evaporators.
Dry Expansion Evaporator
An evaporator where the refrigerant liquid completely vaporizes in a single pass through the tubes.
Working Process of Dry Expansion Evaporator
Typical Applications: Commonly used in cold storage or ice storage air conditioning systems.
Advantages
- Low refrigerant charge
- Requires no or only a small receiver
- Facilitates oil return to the compressor
- Minimal cooling loss
- Reduced risk of freezing
Disadvantages
- Relatively low heat transfer coefficient
Flooded (Recirculating) Evaporator
Definition: An evaporator where the refrigerant liquid requires several circulation cycles to completely vaporize.
Features: Has a relatively high heat transfer coefficient; but large size, requires a large refrigerant charge, higher operating costs.
Flooded Shell-and-Tube Evaporator
Advantages
- Compact structure
- Good heat transfer
- Easy installation and use
Disadvantages
- Requires large refrigerant charge
- Slightly higher evaporation temperature at the bottom reduces the effective temperature difference
- Difficult oil return for fluorocarbon systems
- Risk of refrigerant freezing
Other Types of Evaporators
Other types include vertical tube-type chillers and direct expansion air coolers.
Furthermore, some refrigeration systems also include intermediate coolers and subcoolers, whose principles are similar to general heat exchangers.